1. Field of the Invention
The present invention relates to an alternating current (AC) and direct current (DC) power supply device, and more particularly, to an AC-DC switching mode power supply (SMPS) device, in which a normal power source applied from the outside is converted to an AC voltage or a DC voltage having a predetermined voltage level and is transmitted to a load without an additional wiring, and in which not only AC but also DC is supplied to the load by using normal power and power of a solar cell; particularly, the power of the solar cell is first supplied as DC power or residual power remaining after charging a battery is converted to AC via an inverter to replace the AC power of the normal power source or to allow the power to be transmitted to the outside. Accordingly, AC and DC power may be supplied simultaneously, and moreover, power of the solar cell may be efficiently used.
2. Description of the Related Art
As the energy and environment crisis has recently increased, power production by using alternative energy sources such as power produced by solar cells and the efficient use of power are emphasized, and the use of solar cells in homes is a trend on the increase. Moreover, techniques for manufacturing power supply devices that are capable of using energy effectively and efficiently by total power management are also increasingly being developed.
In general, a normal power supply consists of a HOT wire (+) via which a high voltage-level AC power is supplied, a neutral wire (−) via which a relatively low voltage-level power is supplied compared to the HOT wire (+), and a ground wire GND provided to prevent harm to humans due to an electric shock or an electric leakage. However, it is difficult to use DC power directly from the normal power supply without a power converter that is suitable for various loading capacities.
Some electric appliances, such as an air conditioner, a washing machine, or a refrigerator, require AC power, but there are also products which use DC power by converting AC power. Most DC power produced by solar cells is converted to AC power for use.
Due to switching loss in converters or inverters for converting AC power to DC power or DC power to AC power, however, loss in power conversion is caused.
However, an AC-DC power supply device according to an embodiment of the present invention may be useful as follows.
For example, since the time range of power consumption is highly concentrated depending on the types of use, homes may conclude a certain contract with a power supply company to transmit a predetermined amount of power that is generated by using solar cells during the daytime to the power supply company via, for example, a grid line connection, and the power may be supplied to industrial or commercial facilities during the time range when a high power consumption is required, and at night when a large amount of power is used temporarily, a portion of the power produced by the solar cells at homes and charged thereby may be used. Consequently, the AC-DC power supply device according to an embodiment of the present invention may function like a huge battery.
KR 2012-0089039, filed by the inventors prior to the present application, discloses an AC-DC power supply device in which a normal power source and a battery are used to simultaneously supply AC and DC power. However, as described above, a system allowing efficient use of an alternative power source generated by a solar cell is additionally required.